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TO ALL @HOM IT MAY CONCERN:

GEORGE F. WILSON-,- 0F EAST PROVIDENCE- RHODE-ISLAND.

Lem" Patent 'Na 75,330, ma March 10,1868.

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Be it known that I, GEORGE F'. WxLsoN, of East Providenc.ein the county of Providence, and 4State 'of Rhode Island, have invented anenr and improved Mode of -Drying Acid Phosphate of Lime as prepared finder Horstords patents; 'and Ido hereby declare that the following is a, full and exactdescri'ption thereof, reference- I being had to the accompanying drawings, and to the letters of referencemarked thereon. The object of this myinvention is to provide a continuous and economical drier, bymeansof. which the acid phosphate of lime, made substantially in accordance with the -patents of E. N. Horsford, above referred to, and granulated according to the method described in the application for a patent of George F. Wilson, bear'- 'ing even date therewithfmay, by'artiiicial heat, be rendered suiciently brittleto bel-readily reduced to-powder.

I h'ave dried the acid on cloth scrays, so arranged in an apartment thaba current of airmust sweep over the surface of the acid. By changing the relative position of the scrays from tiine to time, so as to bring them at last into the most heated and freshestv atmosphere, this method proved successful. I havealso'dried the acdlon o peu sclays exposed tothe sun, and on endless aprons in a chamber of heated air. :But thearrange-A ment I- prefer fonobtaining a continuous current of dry, heated air is the followinv:

I t consists. essentially of `a. chamber vthrough whichslowly circulates a. current of highly-heated air, in

which chamber are maintained numerous wide, thin vertical sheets of granulatelacid phosphate-of lime, mixed with farinaceous matter, supported each by two parallel frames of lattice-work one and o quarter inch apart,

` extending from top to bottom of the chamber, so arranged that at intervals a quantity Ofdrigd acid is dis- -charged' at the bottom, and a corresponding quantity .of fresh acid received at the'top. The accompanying diagrams illustrate the relations' of the parts of the apparatus and their'modes of action.

Figure 1 is a view of one 'side of thevch'amber, or a vertical section.

Figure 2 presents a view at right'angles to that in iig. I, also a vertical section.

Figure 3 shows the construction of a single lattice-frame. A

The latticework shown in iig. 1, e e e e, and in ii'g'. 3, e e"e e', consists of narrow slats with parallel bevelled edges fastened to the upright frames dd d d, the' slats having an inclination tolthehorizon of about forty-iive degrees. Two such lattice-framesface each other` like two window-blinds, with Aan intervalof aninch. and a quarter` between the frames, and shown in iig. 3,' as mentioned -above,'and"the' slats of both vinclining downward and toward the intervening space.

In g. 2, which exhibits an end view of the lattice-frames, are Vshown end views'of aseres of revolving troughs, there being one placed under each pair of lattice-frames to receive the acid as it passes through it..

, The lattice-work 4in detail is exhibited in iig. 3, which presents a section at right angles to its horizontal length.-

` The troughs g g g' gare also given.

Iniig. 1,'at Z l, is the iron axle, -by means of which, through the crank t, the trough is revolved, and the pin f,.hy which the measure of movement of the trough is limited to one quarter' of arevolution at each interval. a a represents the hopper, into whichthe dried acid' discharged from the .troughs is received, aud along the bottom of which it is conducted bya screw-worm, h h, to be emptied into the box at the foot of the-elevatorv 'i z' 1.'. -m m m m are brick walls enclosing the chamber. 7c c are the stoves and pipes forheating. 'At u u, Sie,"

are steam-pipes, fulilling the same oiice, and protected by tin shields from the dry acid. n n is the recess in the door above,`in which the granulated acid to 'be dried is received. rg? are openings for -the admission of fresh nir to-be heated by the stoves andpip`es k, or by the coils of steam-pipes ,tt u, &c. 'pp are iron tubes for the escape of the air charged with moisture from the drying acid. z z isan elevator for conveying the` dried acid tothe door abo-ve.

The mode of operating the drier is'as follows: The stoves having been tired,- or the steam admittedto the coilsfor both, dried granulated acid is received iu the recept'aclenin, and the material distributed in the iiues.l

between the lattice-frames till 'the lattices are filled, and the-troughs g .gghaving the position indicated inig. 8, first filling, and then preventing the fnrtherdownward 'passage of the a'cid. The trough is then quickly revolved in th'e direction of the arrow, iig. 8, from c to b, "-throngha' quarter of a revolution, bringing theside c into the position occupied at the outset by 6. As the supportati the bottom ofthe column is'withdrawn, by placing under-,it an empty trough, the.'eolumn of acid drops to fill 'the trough, leaving anempty space at the top. This is a-t once filled from the supply of' fresh undried acid in n n. After allowing the column to remain a certain length oi' time, the trough is revolved through another quarter ofza revolution; the column of'granulated acid drops; avacant spacereappears at the top, which is again filled with fresh acid.

` By repeating these movements, with sucient intervals to secure the thorough drying` of the acid before it reaches the bottom, the process is complete and continuous. .As-each trough is emptied, the carrier or screwy worm moves the dried acid forward to the foot of the elevator, where it is caught aud'removd to the apartment above.

What I claim, -and desire to secure by Letters Patent of the-United States, is Myirnproved process of drying thegranulatcdcid phosphate of lime by exposing the same to contin-A uous currents of heated air on both' sides of the columns thereof, substantiallyl as and for the purposes described. 2. The application of the improved epparatus, constructed and operated substantially as described for the -purpose aforesaid.

8. The arrangement of the revolving troughs, or their equivalent, combined with the vertical-lattice-lines, substantially as above described, by which the process of drying is rendered uniform and continuous.

' I '.GEQ. F. WILSON.. Witnesses:

`WILLIAM Heben, f w

WINsLow WARREN, Jr. 

